The present invention relates generally to the field of farm implements. Specifically, it relates to lift apparatuses for cultivators, air seeders, and the like.
Cultivators use a series of downwardly extending ground breaking blades to dig out furrows in which seeds are placed. Such blades are also present on air seeders and used to create furrows in which seeds are placed. To allow for transport of the farm implement on public or private roads, as well as for turning it around at the end of a cultivating or seeding row, the blades must be vertically adjustable to bring the blades clear of the earth.
Current versions of cultivators and air seeders have mechanical lift systems that use a wide variety of parallelogram linkages in complex mechanical systems. These linkages and systems significantly increase the manufacturing costs of the cultivators and air seeders, and the elaborate systems and large numbers of moving parts of these lift systems also increase maintenance costs.
Other systems known in the art use a hydraulic cylinder to raise or lower a farm implement. Most systems of this type utilize a caster wheel at the end of the hydraulic cylinder piston. The constant jarring and rotational movement of the hydraulic shaft causes continued abrasion and wear on the piston shaft, cylinder wall, and its seals, causing leakage and premature failure of the device. U.S. Pat. No. 2,979,140 to McKenzie teaches the use of a cylinder and caster shaft coaxial with, but separate from the hydraulic piston shaft. McKenzie, however, does not allow unrestrained vertical adjustment of the blade position. McKenzie severely constrains movement of the caster shaft unless the operator manually adjusts a nut to allow each such movement. Movement of the shaft is so severely restrained in McKenzie as to make its teaching useless for achieving the immediate elevating action needed to allow road travel of an implement like that described.
It would be desirable for a cultivator or air seeder to be freely adjustable from a normal operating position to an elevated transport position without the need for a physical manual adjustment by the operator of the cultivator or air seeder. It would further be desirable to provide a cultivator or air seeder that eliminates the need for complex parallelogram linkages, and which allows adjustment of blade position while the implement is in operation.